This recipe was brought over from Scotland. Best made with real butter, these are rich and delicious. Be careful not to overwork the dough, however, or the cookies will be tough. Rice flour can be found in most health food stores.
Preheat the oven to 350 degrees F. Cream the butter with the sugar. Add the flours and blend well. Roll out the dough directly onto an ungreased 10-inch by 15-inch baking sheet. Trim the edges and prick all over with a fork. Bake for 15 minutes, then reduce the oven temperature to 300 degrees F and continue baking for 30 minutes. Cut into squares while still warm.